The invention relates to a dryer for drying continuously conveyed products and to a method for drying continuously conveyed products, with the features of the preamble of the independent patent claims.
In textile processing there are applied dryers in a multitude of different embodiment forms for drying threads or material webs which have been treated with water or other media. For drying, for example heated air is applied which vapourises the fluids, for example the water, and leads away the water vapour.
Such driers are also applied with the sizing of threads. After the application of the sizing material onto the threads, excess water must be removed from the threads in a drying procedure.
The productivity of such driers is dependent on various parameters. The higher the temperature of the dryer is selected, the higher is the drying effect and the more quickly the installation may be operated. The temperature may however not be chosen infinitely high since too high temperatures would destroy the threads consisting of plastic or containing plastics.
A high drying performance may furthermore be achieved in that simultaneously several threads in a thread assemblage are led through the dryer. At the same time it is possible to lead several layers of thread over one another through the dryer. However as soon as too large a number of layers of threads lie over one another there exists the danger that threads lying in the inside of the thread assemblage are no longer sufficiently dried.
The problem of the destruction of threads on account of too great a heat is particularly large with a standstill of the installation, for example caused by a thread breakage. If the installation stands still, the water located on the threads in the dryer is vapourised. As soon as all the water has vapourised the thread itself heats up. If the heat in the dryer with a standstill is not immediately led away, it may lead to a destruction of the threads. It is therefore already known with such dryers to provide openable flaps which with a standstill of the installation are opened automatically or by hand.
It is the object of the present invention to further improve the known dryer and drying method with respect to the productivity and at the same time to reduce the risk of the destruction of the threads by way of too high temperatures. The introduction of the threads into the dryer by way of the operating personnel is furthermore to be simplified. According to the invention this object is achieved with a dryer for drying continuously conveyed products and with a method for the stoppage or temporary interrupton of the drying, with the features of the characterising parts of the independent patent claims.
The dryer for drying continuously conveyed products is in particular applied for drying a sized thread assemblage. It is however also conceivable to apply such driers in other fields of application such as for drying material webs. The dryer comprises a first dryer arrangement and a second dryer arrangement, between which there is formed a passage for leading through the products to be dried. The first dryer arrangement and the second dryer arrangement are designed movable with respect to one another such that the passage for leading through the product in a stoppage state of the dryer is larger, i.e. has a larger cross section, than in an operational state. The provision of two dryer arrangements permits an effective drying of larger thread assemblages, since heat acts on the thread assemblage from two sides. The danger of damage to the threads by too high temperatures is however reliably reduced in that the dryer with an installation standstill may be moved into a stoppage state. Since in the stoppage state the passage is formed larger than in the operational state, the heat may escape. The danger of a heat accumulation is avoided.
Simultaneously after a thread breakage the broken thread or threads, by the operating personnel in a simple manner may be led through the passage for leading through the product, since this passage in the stoppage state is larger than in the operational state.
In a preferred embodiment example the first and the second dryer arrangement are arranged over one another and the second upper-lying dryer arrangement is designed in a liftable manner. With an installation standstill the second dryer arrangement is lifted into the stoppage state. With this the dryer arrangements remain essentially parallel to one another. In the operational state the cross section of the passage corresponds roughly to the cross section of the thread assemblage. In the lifted stoppage state the passage has a larger cross section. The hot air may laterally escape between the dryer arrangements. Simultaneously a new thread may be led by the operating personnel in a simple manner from the side of the dryer through the gap between the lower edge of the upper dryer and the upper edge of the lower dryer.
In this context it is advantageous when the space around the dryer is free from installations, e.g. supports or likewise, so that the access to the gap is not made difficult.
In a further preferred embodiment example the dryer arrangements are designed as warm air dryers in which a warm gas flow may be led preferably roughly parallel along the product.
For heating the air flow the dryer may be provided with one or more gas burners. Advantageously each dryer arrangement comprises several, preferably two gas burners. The gas burners may be individually controllable. With this it is possible to achieve a homogeneous temperature distribution of the air over the whole width of the dryer. The heating-up of the air flow by way of a vapour or thermo-oil damper register is likewise conceivable.
In a further preferred embodiment example the passage between the first and the second dryer arrangement is laterally sealed. The lateral sealing prevents heat loss in the normal operating condition.
According to a further aspect of the invention there is provided a dryer for drying a continuously conveyed product, in particular for drying a sized thread assemblage, which comprises a first and a second drier arrangement. The product to be dried is led through between the first and the second dryer arrangement. According to this aspect of the invention the first dryer arrangement and the second dryer arrangement are designed as a warm air dryer in which a warm gas flow is readable parallel along the product. Since the drying is effected from two sides of the product it is possible to dry thicker thread assemblages without there existing the danger that the heat does not reach the threads lying further inwards in the assemblage. The quantity of simultaneously dried threads may therefore be increased with a treatment speed which stays the same. The first and the second dryer arrangement are at the same time preferably designed symmetrical to one another with respect to a plane of symmetry. The plane of symmetry lies roughly in the middle of the path for the product to be dried. Thus the invention, with a dryer arrangement known per se with a warm air flow parallel to the product, envisages providing a second identical dryer arrangement on the opposite side of the product.
According to the method according to the invention for stopping or for the temporary interruption of the drying of a continuously conveyed product, in particular a dryer as previously described is applied. The movement of the product is stopped, for example on account of a thread breakage. In order to prevent there resulting a heat accumulation in the inside of the dryer, which could lead to a destruction of the products, the first dryer arrangement is moved with respect to the second dryer arrangement such that the passage for the product formed between the first and the second dryer arrangement enlarges. In a preferred embodiment example the second dryer arrangement lying above the first dryer arrangement is lifted.
Of course further embodiment examples are conceivable which fall under the scope of the invention. Thus e.g. it is conceivable to fold up or laterally displace the upper lying second dryer arrangement instead of lifting it. It would also be conceivable to laterally displace or sink the lower lying first dryer arrangement. It is furthermore likewise conceivable to provide dryer arrangements lying laterally next to one another.